Low-water-consumption rinsing and/or washing device, and dishwashing machine featuring such a device

ABSTRACT

A spray arm assembly for a dishwashing machine includes at least one arm rotationally mounted about an axis, the arm including an internal cavity for receiving a pressurized service fluid and being provided with a plurality of spraying nozzles for spraying service fluid from said arm in the form of spray jets. The arm is shaped so that its opposite ends radially extend from the rotation axis in a manner diametrically opposite to each other about the rotation axis. The spraying nozzles are numbered, sized and positioned such that a total flow rate of service fluid delivered in use by the spraying nozzles at each concentric nozzle location circumference traced about the rotation axis of the arm during a complete rotation of the arm increases as a function of the radius of said nozzle location circumference.

TECHNICAL FIELD

The present application relates to a rinsing and/or washing device for an electric household appliance, specifically for a dishwashing machine of the professional type, able to drastically reduce the consumption of water. The application further relates to the electric household appliance equipped with such a device.

BACKGROUND

A washing/rinsing device for a dishwashing machine including a rotating arm provided with spraying nozzles and epicyclic movement in order to perform a better distribution of washing/rinsing fluid inside the washing chamber of the dishwashing machine, usually accessible through a front pivoting door, is known from EP1050263.

However, the known device, in addition to be costly and complex to be manufactured, has considerable dimensions and in any case does not solve the problem of drastically reducing the amount of water needed by the machine for carrying out the washing cycle and, in particular, the rinsing cycle, simultaneously obtaining good washing results on the dishes to be treated.

Indeed, a study internally carried out by the Applicant has recently brought to light that all the dishwashing machines manufactured nowadays, in order to ensure a “minimum guaranteed” delivery of water in all points of the washing chamber, deliver more water than needed in many points of the chamber itself. This drawback causes a considerable waste of water resources and, above all, of energy resources, in particular in dishwashing machines for professional use (for bars, restaurants, communities, etc.) which, even if largely work with recirculated water (closed cycle), must however resort to the water from the water network (open cycle) at least for the rinsing cycle and, in all cases, must heat the washing and rinsing water before delivering it onto the dishes at relatively high temperatures for hygienic reasons.

It would be desirable to provide an improved rinsing and/or washing device for an electric household appliance, in particular a dishwashing machine for professional use, which overcomes the aforesaid drawbacks, allowing a high reduction of water and energy consumptions of the dishwashing machine, in particular during the rinsing cycle, and at the same time, which is simple and cost effective to be manufactured and managed, of reduced size and high reliability, in particular with regards to possible obstructions in use of the water delivering jets. It would also be desirable to provide a dishwashing machine provided with such a device which, therefore, has reduced energy and water consumptions.

SUMMARY

In one aspect, a rinsing and/or washing device for an electric household appliance, in particular a dishwashing machine, is thus provided as defined in claim 1.

In particular, a device comprises at least one arm rotationally mounted about a generally vertical axis in a washing chamber of the electric household appliance, e.g. immediately either over or under a container basket of the dishes to be washed. The arm delimits a cavity therein connected in use to delivering means of a pressurized service fluid, e.g. a washing and/or rinsing fluid, of the electric household appliance and is provided with a plurality of spraying nozzles arranged and oriented, in use, towards the dishes to be washed, reciprocally spaced in the direction of length of the arm and communicating with the internal cavity of the latter, so as to determine in use the exiting of the service fluid from the arm in form of jets directed against the dishes.

The arm is shaped so that its opposite ends radially and overhangingly extend from the rotation axis, in a manner diametrically opposite to the rotation axis itself, according to a configuration which is generally known; however, in combination with such a feature, the number, the size and the position of the existing nozzles are chosen so that the total flow rate of the service fluid delivered in use by the nozzles present on the arm at each concentric circumference that the same nozzles trace about the rotation axis of the arm during a complete rotation of the same is an increasing function, in particular linearly increasing, of the radius of such a circumference.

In this manner, the zones of the basket closest to the rotation axis of the arm are reached by less water, while more water is directed towards the furthermost zones, to reach which the nozzles of the arm, during the rotation of the same, must cover a larger area and, thus, must necessarily have a lower water delivery “density” (ml/cmq), with the flow rate being equal. By appropriately balancing the flow rates during the design of the arm and of the nozzles thereof, it is thus possible to obtain an essentially constant water delivery “density” throughout the dish-holding basket. Assuming to always use the minimum amount of water deemed sufficient to obtain adequate cleaning results (approximately 2.7 litres per basket), simple calculations allow to establish that by means of the device of the invention a saving of water, which may reach even 30% in the rinsing cycle, may be obtained, with a consequent, drastic reduction of water consumptions and, above all, of energy consumptions of the dishwashing machine equipped with such a device.

In one implementation, the arm is provided with only two types of nozzles, namely with first nozzles, adapted to deliver in use a first predetermined flow rate of service fluid, and second nozzles adapted to deliver in use a second predetermined flow rate of service fluid, lower than the first flow rate; and the nozzles are arranged along opposite longitudinal portions of the arm, which extend radially and overhangingly from a central securing portion of the arm to the rotation axis of the same so that at least one nozzle of a first of the opposite longitudinal portions of the arm is arranged in a radially symmetric position with respect to at least one nozzle of a second of the opposite longitudinal portions of the arm, so as to trace in use the same circumference traced in use by the nozzle of the second longitudinal portion of the arm and therefore may add this to its own water flow rate.

In this manner, it is possible to obtain the desired water distribution with only two types of different nozzles (instead of with a plurality of nozzles of progressively increasing flow rate arranged at progressively increasing distances from the rotation axis), as long as these are appropriately positioned in an asymmetric manner along the arm so that, for certain circumferences they trace in use, the flow rates delivered thereby are appropriately added, while for other circumferences this does not occur. On one hand, this implies a drastic reduction of production and assembly costs of the washing device according to the invention and, on the other hand, avoids the risk that nozzles of excessively small flow rate (thus with a reduced water passage section) may be obstructed in use due to the dirt which is removed from the dishes.

BRIEF DESCRIPTION OF DRAWINGS

Further objects and advantages will be apparent from the following description of a non-limitative embodiment thereof, provided only by way of example and with reference to the figures of the accompanying drawing, in which:

FIG. 1 diagrammatically shows a perspective view of a dishwashing machine provided with a washing device manufactured according to the invention;

FIG. 2 diagrammatically shows a side elevation view of the washing device used in the dishwashing machine in FIG. 1 compared to a graph which provides for the distribution of the washing/rinsing water obtainable according to the invention; and

FIG. 3 diagrammatically shows a bottom plan view of the washing device in FIGS. 1 and 2.

DETAILED DESCRIPTION

In figures from 1 to 3, numeral 1 indicates as a whole a rinsing and/or washing device for an electric household appliance 2, in particular a dishwashing machine for professional use, of the front loading type in the example shown.

The dishwashing machine 2 comprises in particular a washing chamber 3 accommodating at least one container basket 4 (known) for the dishes 5 to be washed, the washing device 1 and delivering means 7 of a pressurised service fluid 8, e.g. washing and/or rinsing water, towards the device 1, in this case towards an inlet head 10 arranged in the washing chamber 3 with its own symmetry axis A arranged essentially vertical and connected to the washing/rinsing device 1 in the manner disclosed below.

The delivering means 7 of the pressurized water are known and comprise, in this case, a pump 11, a tank 12 in which the water delivered onto the dishes 5 through the inlet head 10 and the device 1 is collected in use, and network water feeding means 13, the pump 11 being able to use both the network water and the water in the tank 12.

The device 1 comprises at least one arm 20 rotationally mounted about axis A, which is generally vertical, within the washing chamber 3 of the electric household appliance 2, e.g. in a preferred embodiment, immediately over (or under) the container basket 4, in this case, idly and fluid-tightly mounted in a known manner and thus not described in detail for simplicity, on the inlet head 10 with its own central assembly portion 21.

The arm 20 delimits therein a cavity 22 (FIG. 3) connected in use to the delivering means 7 of the water through the inlet head 10 and is provided with a plurality of spraying nozzles 23 arranged oriented in use towards the dishes 5 to be washed, reciprocally spaced in the sense of length of the arm 20 and communicating with the internal cavity 22 of the latter, so as to determine in use the exiting of the service fluid 8 (water or water and detergent) from arm 20 in the form of jets 24 (FIG. 2) directed towards the dishes 5.

In accordance with the description, the arm 20, according to a first aspect of the invention, is shaped so that its opposite ends 25,26 radially and overhangingly extend, in use, from rotation axis A in a manner diametrically opposite with respect to the rotation axis A itself; in combination with such a feature, the arm 20 is constructed so that the number, the size and the position of the existing nozzles 23 is such that the total flow rate of the service fluid 8 delivered in use by the nozzles 23 at each ideal concentric nozzle location circumference C (diagrammatically shown with a dashed line in FIG. 3) which is traced by the nozzles 23 themselves about the rotation axis A of the arm 20 during a complete rotation of the same, is an increasing function of the radius of such a circumference.

Specifically, the total flow rate of the service fluid 8 delivered in use by the nozzles 23 at each concentric nozzle location circumference C which they trace about the rotation axis A of the arm 20 during a complete rotation of the same, increases in an essentially linear manner with the radius of the circumferences C, as diagrammatically shown in the graph in FIG. 2.

Substantially, according to the invention, the arm 20 is designed to deliver by means of the nozzles 23 more water the farther the distance of the nozzles 23 from the rotation axis A is. Such a result might be obtained by an arm however shaped and mounted, provided that it is equipped with nozzles of gradually larger opening according to their distance from the rotation axis A; however, in such a manner, the manufacturing cost of the arm 20 would be relatively high and, above all, the opening of the nozzles closest to the axis A would be so small that they risk being obstructed in use by the dirt removed from the dishes 5.

Therefore, according to a non negligible aspect of the invention, the assembly portion 21 to the inlet head 10, known per se, is essentially arranged on the middle line of the arm 20, so as to split the arm into two opposite longitudinal portions 27,28, which are the only parts of the arm 20 provided with the nozzles 23; the portions 27,28 end, on the opposite side of the assembly portion 21, with the ends 25,26, which may be provided (FIG. 3) with propulsion nozzles 30 (known per se) appropriately oriented and constructed so as to determine a tangential pouring of service fluid 8 therethrough, so that the nozzles 30 represent in use reaction thrust generating means for determining the rotation of the arm 20 about the axis A.

Alternatively, the nozzles 30 may be missing and therefore the nozzles 23 (according to a method which is known per se) will be oriented slightly askew with respect to axis A, so as to further determine in use, by means of the ejection from the washing/rinsing jets 24, the reaction rotation movement of the arm 20 about the axis A.

In this manner, the assembly portion 21 serves the two-fold function of securing, in use, the arm 20 to the rotation axis A so that the longitudinal portions 27,28 protrude in use in an essentially symmetric manner from the assembly portion 21 in a radial direction with respect to the rotation axis A; and of making the fluid-tight connection between the inlet head 10 and the corresponding delivering means 7 of the service fluid 8 and the internal cavity 22 of the arm 20. The latter is obtained either by manufacturing the portions 27,28 as tubular elements closed at the ends 25,26, or by manufacturing the portions 27,28 by means of two reciprocally coupled concave parts (e.g. made of pressed metal sheet).

In combination with the structure of the arm 20 described heretofore, the nozzles 23 are arranged along the opposite longitudinal portions 27,28 of the arm 20 so that at least one nozzle 23 of the portion 27 is arranged in a radially symmetric position with respect to at least a corresponding nozzle 23 of the portion 28, so that these two nozzles 23 trace in use the same circumference C, therefore adding their flow rates of service fluid 8 towards the basket 4, meaning that the jets 24 produced therefrom will insist, in use, on the same area (in this case, defined by a circular crown centred on axis A) of the basket 4.

According to a preferred but not limitative embodiment of the invention, the arm 20 is provided with only two different types of nozzles 23, namely with nozzles 23 b adapted to deliver in use a first predetermined flow rate q1 of fluid 8, and with nozzles 23 c adapted to deliver in use a second predetermined flow rate q2 of service fluid 8, smaller than the flow rate q1 (the relation q1>q2 thus applies).

The nozzles 23 b and 23 c are further arranged according to an asymmetric configuration with respect to axis A so as to generate in use, with the nozzles 23 b and 23 c of the portion 27, jets 24 which may be added (meaning that they insist on the same areas of the basket 4 in use) or not, to the jets 24 generated by the nozzles 23 b and 23 c of the portion 28.

In particular, the longitudinal portion 27 of the arm 20 carries a nozzle 23 c arranged at a predetermined radial distance from the assembly portion 21 so as this traces in use a first circumference C1 of radius R1 about the rotation axis A, and a pair of nozzles 23 b arranged in tandem at a radial distance from the assembly portion 21 so that each of them traces in use a second circumference C2 of radius R2 greater than R1 and a third circumference C3 of radius R3 greater than R2 about the rotation axis A, respectively.

The opposite longitudinal portion 28 of the arm 20 instead carries a nozzle 23 b arranged at a radial distance from the assembly portion 21 so that this traces in use a fourth circumference C4 of radius R4 about the rotation axis A; gradually moving away from axis A, there is a second nozzle 23 c arranged at a radial distance from the assembly portion 21 so that this second nozzle 23 c of the portion 28 traces in use the same circumference C2 traced by a nozzle 23 b of the portion 27; and a third nozzle 23 b arranged at a radial distance from the assembly portion 21 so that it traces in use the same circumference C3 traced by a nozzle 23 b of the portion 27.

The position of the first nozzle 23 b (in the sequence counted from axis A) of the portion 28 is finally chosen so that the radius R4 of the circumference C4 which it describes in use about the axis A is greater than the radius R1 of the circumference C1 traced in use by the first nozzle (again according to a sequence counted from the axis A) of the portion 27 and smaller than the radius R2 of the circumference C2 traced in use by both the second nozzle 23 b of the portion 27, and the second nozzle 23 c of the portion 28.

In this manner, the areas of the basket 4 progressively further away from the axis A defined by circular crowns placed at the circumferences C1-C4 and each having a radial width depending on the opening angle of the jets 24 generated by the nozzles 23 tracing each circumference each time (therefore, areas of progressively larger dimensions), are in use sprinkled by progressively increasing flow rates of service fluid 8, called Q1, Q2, Q3, Q4, the values of which will depend on the position (circumferences C1-C4) and type (nozzles 23 b and 23 c) of the nozzles 23 from which each circular crown is sprinkled in use.

According to the description and the illustration in FIG. 3, the aforesaid overall flow rates will have the following values:

Q1=q2;

Q2=q1;

Q3=q1+q2

Q4=q1+q1

It is thus apparent that by appropriately choosing the position and sizes of the nozzles 23, each zone of the basket 4 may be invested in use by a total amount of water L which remains approximately constant, regardless of the distance from the rotation axis A which is taken into account. 

1. A rinsing and/or washing device for a dishwashing machine, comprising at least one arm rotationally mounted about a generally vertical axis (A) in a washing chamber of the dishwashing machine, the arm delimiting a cavity therein connected in use to delivering means of a pressurized service fluid and being provided with a plurality of spraying nozzles arranged and oriented, in use, for spraying towards dishes to be washed, the spraying nozzles spaced along a length of the arm and communicating with the internal cavity (22) of the arm, so as to determine in use exiting of service fluid from the arm in form of jets directed against dishes; wherein said arm is shaped so that its opposite ends radially and overhangingly extend from the rotation axis, in a manner diametrically opposite to the rotation axis itself; characterized in that, in combination, the number, the size and the position of the spraying nozzles is such that the total flow rate of service fluid delivered in use by the spraying nozzles at each concentric nozzle location circumference traced about the rotation axis of the arm during a complete rotation of the arm is an increasing function of the radius of said nozzle location circumference.
 2. A device according to claim 1, characterized in that the total flow rate of service fluid delivered in use by the spraying nozzles at each concentric nozzle location circumference traced about the rotation axis of the arm during the complete rotation of the arm increases in an essentially linear manner with the radius of said nozzle location circumference.
 3. A device according to claim 2, characterized in that said arm has an assembly portion for securing it to said rotation axis arranged essentially on the middle line of the arm, so that opposite longitudinal portions of the arm, provided with said spraying nozzles and ending with said opposite ends of the arm, protrude in use in an essentially symmetric manner from the assembly portion in radial direction with respect to the rotation axis.
 4. A device according to claim 3, characterized in that said spraying nozzles are arranged along said opposite longitudinal portions of the arm so that at least one spraying nozzle of a first of said opposite longitudinal portions of the arm is arranged in a radially symmetric position with respect to at least one spraying nozzle of a second of said longitudinal portions of the arm, so that said at least one spraying nozzle of said first longitudinal portion of the arm traces in use the same nozzle location circumference traced in use by said at least one spraying nozzle of said second longitudinal portion of the arm.
 5. A device according to claim 4, characterized in that said arm is provided with first spraying nozzles adapted to deliver in use a first predetermined flow rate of service fluid; and with second spraying nozzles adapted to deliver in use a second predetermined flow rate of service fluid, smaller than said first predetermine flow rate.
 6. A device according to claim 5, characterized in that said arm is provided only with said first and second spraying nozzles.
 7. A device according to claim 6, characterized in that the first of said opposite longitudinal portions of the arm carries one second spraying nozzle arranged at a predetermined radial distance from the assembly portion so as to trace in use a first nozzle location circumference about said rotation axis, and a pair of first spraying nozzles arranged in tandem at respective radial distances from the assembly portion so that each of them respectively traces in use a second and a third nozzle location circumference about said rotation axis.
 8. A device according to claim 7, characterized in that the second longitudinal portion of the arm, opposite to the first, carries: one first spraying nozzle arranged at a radial distance from the assembly portion so as to trace in use a fourth nozzle location circumference about said rotation axis; one second spraying nozzle arranged at a radial distance from the assembly portion so as to trace in use said second nozzle location circumference about said rotation axis; and one first spraying nozzle arranged at a radial distance from the assembly portion so as to trace in use said third nozzle location circumference about said rotation axis.
 9. A device according to claim 8, characterized in that said fourth nozzle location circumference has a radius greater than that of said first nozzle location circumference and smaller than the radius of said second nozzle location circumference.
 10. A device according to claim 9, characterized in that said arm is provided with reaction thrust generating means to determine in use the rotation about said axis.
 11. A spray arm assembly for a dishwashing machine, comprising at least one arm rotationally mounted about an axis, the arm including an internal cavity for receiving a pressurized service fluid and being provided with a plurality of spraying nozzles for spraying service fluid from said arm in the form of spray jets; wherein said arm is shaped so that its opposite ends radially extend from the rotation axis in a manner diametrically opposite to each other about the rotation axis; characterized in that, the spraying nozzles are numbered, sized and positioned such that a total flow rate of service fluid delivered in use by the spraying nozzles at each concentric nozzle location circumference traced about the rotation axis of the arm during a complete rotation of the arm increases as a function of the radius of said nozzle location circumference.
 12. The spray arm assembly according to claim 11, characterized in that the total flow rate of service fluid delivered in use by the spraying nozzles at each concentric nozzle location circumference traced about the rotation axis of the arm during the complete rotation of the arm increases in an essentially linear manner with the radius of said nozzle location circumference.
 13. The spray arm assembly according to claim 12, characterized in that said arm has a central assembly portioned for securing it to a dishwashing machine, said rotation axis extending through said central assembly so that opposite longitudinal portions of the arm, provided with said spraying nozzles and ending with said opposite ends of the arm, protrude in use in an essentially symmetric manner from the assembly portion in radial direction with respect to the rotation axis.
 14. The spray arm assembly according to claim 13, characterized in that said spraying nozzles are arranged along said opposite longitudinal portions of the arm so that at least one spraying nozzle of a first of said opposite longitudinal portions of the arm is arranged in a radially symmetric position with respect to at least one spraying nozzle of a second of said longitudinal portions of the arm, so that said at least one spraying nozzle of said first longitudinal portion of the arm traces in use the same nozzle location circumference traced in use by said at least one spraying nozzle of said second longitudinal portion of the arm.
 15. The spray arm assembly according to claim 14, characterized in that said arm is provided with first spraying nozzles adapted to deliver in use a first predetermined flow rate of service fluid; and with second spraying nozzles adapted to deliver in use a second predetermined flow rate of service fluid, smaller than said first predetermine flow rate.
 16. The spray arm assembly according to claim 15, characterized in that the first of said opposite longitudinal portions of the arm carries: one second spraying nozzle arranged at a predetermined radial distance from the assembly portion so as to trace in use a first nozzle location circumference about said rotation axis, and a pair of first spraying nozzles arranged in tandem at respective radial distances from the assembly portion so that each of them respectively traces in use a second and a third nozzle location circumference about said rotation axis.
 17. A device according to claim 16, characterized in that the second longitudinal portion of the arm, opposite to the first, carries: one first spraying nozzle arranged at a radial distance from the assembly portion so as to trace in use a fourth nozzle location circumference about said rotation axis; one second spraying nozzle arranged at a radial distance from the assembly portion so as to trace in use said second nozzle location circumference about said rotation axis; and one first spraying nozzle arranged at a radial distance from the assembly portion so as to trace in use said third nozzle location circumference about said rotation axis.
 18. A device according to claim 17, characterized in that said fourth nozzle location circumference has a radius greater than that of said first nozzle location circumference and smaller than the radius of said second nozzle location circumference.
 19. A dishwashing machine including the spray arm assembly of claim 11, comprising: a wash chamber including a dish receiving area; the spray arm assembly of claim 11 mounted for rotation within the wash chamber with the rotation axis essentially vertical; a service fluid delivery system connected to deliver service fluid to the internal cavity of the arm.
 20. The dishwashing machine of claim 19 wherein the spray arm assembly is fluid-tightly mounted on an inlet head within the washing chamber. 